title: Helicobacter pylori infection and esophageal cancer risk: an updated meta-analysis.
abstract: OBJECTIVE
  To clarify the association between Helicobacter pylori (H. pylori) infection and the risk of esophageal carcinoma through a meta-analysis of published data.
  
  
  METHODS
  Studies which reported the association between H. pylori infection and esophageal cancer published up to June 2013 were included. The odds ratios (ORs) and corresponding 95%CIs of H. pylori infection on esophageal cancer with respect to health control groups were evaluated. Data were extracted independently by two investigators and discrepancies were resolved by discussion with a third investigator. The statistical software, STATA (version 12.0), was applied to investigate heterogeneity among individual studies and to summarize the studies. A meta-analysis was performed using a fixed-effect or random-effect method, depending on the absence or presence of significant heterogeneity.
  
  
  RESULTS
  No significant association between H. pylori infection and esophageal squamous cell carcinoma (ESCC) risk was found in the pooled overall population (OR = 0.97, 95%CI: 0.76-1.24). However, significant associations between H. pylori infection and ESCC risk were found in Eastern subjects (OR = 0.66, 95%CI: 0.43-0.89). Similarly, cytotoxin-associated gene-A (CagA) positive strains of infection may decrease the risk of ESCC in Eastern subjects (OR = 0.77, 95%CI: 0.65-0.92), however, these associations were not statistically significant in Western subjects (OR = 1.26, 95%CI: 0.97-1.63). For esophageal adenocarcinoma (EAC) the summary OR for H. pylori infection and CagA positive strains of infection were 0.59 (95%CI: 0.51-0.68) and 0.56 (95%CI: 0.45-0.70), respectively.
  
  
  CONCLUSIONS
  H. pylori infection is associated with a decreased risk of ESCC in Eastern populations and a decreased risk of EAC in the overall population.
authors.affiliation: Fa-Jun Xie, Yi-Ping Zhang, Lan Shao, Xin-Min Yu, Department of Medical Oncology, Zhejiang Cancer Hospital, Hangzhou 310022, Zhejiang Province, China.
authors.forename: Fa-Jun
authors.initials: FJ
authors.lastname: Xie
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Zhang
authors.forename: Qiu-Qing
authors.initials: QQ
authors.lastname: Zheng
authors.forename: Hong-Chuan
authors.initials: HC
authors.lastname: Jin
authors.forename: Fa-Liang
authors.initials: FL
authors.lastname: Wang
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.forename: Lan
authors.initials: L
authors.lastname: Shao
authors.forename: De-Hong
authors.initials: DH
authors.lastname: Zou
authors.forename: Xin-Min
authors.initials: XM
authors.lastname: Yu
authors.forename: Wei-Min
authors.initials: WM
authors.lastname: Mao
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology; D001208:Asia / Q000453:epidemiology; D044466:Asian People; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology; D004938:Esophageal Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology; D000077277:Esophageal Squamous Cell Carcinoma; D016481:Helicobacter Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology; D016480:Helicobacter pylori / Q000302:isolation & purification*; D006801:Humans; D016017:Odds Ratio; D011379:Prognosis; D012307:Risk Factors
keywords: Cancer risk; Esophageal carcinoma; Helicobacter pylori; Meta-analysis